Cooling jacket

ABSTRACT

A cooling jacket for cooling an electric motor is provided. The cooling jacket has one or more continuous S-shaped pipes, covering the electric motor, for conducting working fluid, wherein each continuous S-shaped pipe at least has: a forwarding portion and a reversed portion, respectively extending along two circumferential directions which are parallel but opposite to each other; and a turning portion connected between the forwarding portion and the reversed portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application No(s). 100142813, filed in Taiwan, Republic ofChina on Nov. 23, 2011, the entire contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to heat dissipation technology forelectric motor.

2. Description of the Related Art

To maintain the performance and prolong the lifecycle of an electricmotor, the heat generated from a operating electric motor should beappropriately dissipated.

The prior art usually uses a cooling pipe and the working fluid thatflows through the cooling pipe to dissipate the heat generated from theelectric motor. FIG. 1 is a schematic diagram of the cooling pipe in theprior art. In FIG. 1, the electric motor (not shown) is basically in acolumn shape, and, to fit the shape of the electric motor, the coolingpipe extends in a spiral fashion from an inlet to an outlet and coversthe electric motor. From this diagram, it can be seen that the coolingpipe does not cover the areas A and B of the electric motor which isnear the inlet and outlet of the cooling pipe, thus causing heatconcentration in the areas A and B and influencing the entire heatdissipation of the electric motor. Although in some designs the coolingpipe can cover these areas, the working fluid usually loses its kineticenergy when flowing through these areas due to the poor convective heattransfer ability of the fluid in a spiral pipe (from the principles offluid dynamics, the fluid in the spiral pipe has little pressure drop,which leads to a low convective heat transfer rate and poor convectiveheat transfer ability)

It can be noted that the heat dissipating area provided by the coolingpipe and the quantity of the working fluid that flows in the coolingpipe are both limited to the size of the electric motor. Therefore, howto design a cooling device to dissipate more heat in the limited regionsis an important issue which needs to be solved.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a cooling jacket for cooling an electricmotor. The cooling jacket comprises one or more continuous S-shapedpipes, covering the electric motor, for conducting working fluid,wherein each continuous S-shaped pipe at least comprises: a forwardingportion and a reversed portion, respectively extending along twocircumferential directions which are parallel but opposite to eachother; and a turning portion connected between the forwarding portionand the reversed portion.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading thesubsequent detailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a schematic diagram of the cooling pipe in the prior art.

FIG. 2A is a three dimensional (3D) view of the cooling jacket accordingto an embodiment of the present invention. FIG. 2B is an illustrativediagram where the cooling jacket in FIG. 2A is spread into a plane foreasy comprehension.

FIG. 3A is a 3D view of the cooling jacket according to an embodiment ofthe present invention. FIG. 3B is an illustrative diagram where thecooling jacket in FIG. 3A is spread into a plane.

FIG. 4A is a 3D view of the cooling jacket according to an embodiment ofthe present invention. FIG. 4B is an illustrative diagram where thecooling jacket in FIG. 4A is spread into a plane.

FIGS. 5A and 5B shows three sets of continuous S-shaped pipes in acooling jacket 500.

FIG. 6A is a 3D view of the cooling jacket according to an embodiment ofthe present invention.

FIG. 6B is an illustrative diagram where the cooling jacket in FIG. 4Ais “spread” into a 2D plane.

FIG. 7A is a 3D view of the cooling jacket according to an embodiment ofthe present invention.

FIG. 7B is an illustrative diagram where the cooling jacket in FIG. 4Ais “spread” into a 2D plane.

FIG. 8 is a schematic diagram of a two-layered cooling jacket accordingto an embodiment of the present invention.

FIG. 9 shows a combination of the cooling jackets in FIGS. 6A and 7.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

FIG. 2A is a 3D view of the cooling jacket according to an embodiment ofthe present invention. FIG. 2B is an illustrative diagram where thecooling jacket in FIG. 2A is “spread” into a 2D plane for easycomprehension. Although the cooling jacket of the present invention isoriginally designed for high-power and high-accuracy electric motorssuch as motors and power generators, the present invention should not belimited thereto. As shown in FIGS. 2A and 2B, the cooling jacket 200, inaddition to the working fluid inlet 240 and working fluid outlet 250,further comprises “one set” of continuous S-shaped pipe (embodimentswith several sets of continuous S-shaped pipes will be discussed later).The set of continuous S-shaped pipe covers the entire electric motor,and allows the working fluid to flow through the pipe. Thus, the heatgenerated from the electric motor can be dissipated by the flow of theworking fluid, and the electric motor can be kept at a normal operatingtemperature. Generally, the working fluid of the present invention canbe any kind of liquid which has temperature not higher than the normaloperating temperature of the electric motor. For example, the liquid canbe water, lubricant oil, mixed liquid of 50% ethylene glycol and 50%water, or water with anti-freeze agent, however the present inventionshould not be limited thereto. In addition, the liquid in the coolingjacket of the present invention can be propelled by various motors orpumps (not shown in Figs.). The purpose of the present invention is toovercome defects in heat dissipation in the prior art due to limitedcooling area and limited working fluid quantity. The present inventionachieves this purpose by increasing the flow speed of the working fluid(given the same propelling power as that in the prior art). Theprinciple of the present invention will be further described in detaillater.

In comparison between FIGS. 1 and 2A, it can be seen that the coolingjacket of the present invention has a quite different structure fromthat in the prior art. The cooling pipe described in “Description of theRelated Art” is in a spiral shape, but the cooling pipe of the presentinvention is substantially in a continuous S shape. For illustration,the continuous S-shaped piped cooling jacket 200 of the presentinvention can be divided into three parts: the forwarding portion(s)210, the reversed portion(s) 220 and the turning portion(s) 230. Inorder to cover as much of the electric motor as possible, the forwardingportion 210 and the reversed portion 220 are juxtaposed (parallel) toeach other, and both extend along a circumferential direction. Inaddition, the forwarding portion 210 and the reversed portion 220respectively extend in opposite directions (where the forwarding portion210 extends clockwise, while the reversed portion 220 extendscounter-clockwise), thus allowing the working fluid to flow in oppositedirections. The turning portion 230 of the present invention isconnected between the forwarding portion 210 and the reversed portion220 for turning the working fluid 180 degrees. The major differencebetween the prior art and the present invention is the turning portion230. In the present invention, the working fluid has a great pressuredrop when flowing through the turning portion 230, thus increasing theflow speed as well as the convective heat transfer rate (h value, in theunit of W/m2k) there. Since the heat exchanged between the cooling flowand the electric motor is basically in direct proportion to theconvective heat transfer rate, the cooling jacket of the presentinvention can greatly improve the defects of the heat concentrationaround the inlets and outlet of the spiral shaped cooling pipes in theprior art (as shown in FIG. 1).

FIG. 3A is a 3D view of the cooling jacket according to an embodiment ofthe present invention. FIG. 3B is an illustrative diagram where thecooling jacket in FIG. 3A is “spread” into a 2D plane. In FIG. 3B, thecontinuous S-shaped pipe of the cooling jacket 300 has substantially thesame structure as that in FIG. 2B, and can be divided into three parts:the forwarding portion(s) 310, the reversed portion(s) 320 and theturning portion(s) 330. However, different from FIG. 2B, the continuousS-shaped pipe in FIG. 3B has an unequal pipe diameter. Specifically, thepipe diameter of the forwarding and the reversed portions of thecontinuous S-shaped pipe reduce from the working fluid inlet 340 to theworking fluid outlet 350. In a traditional cooling pipe, as flowing in along path, the working fluid will gradually absorb heat, raise itstemperature, and decrease the heat transfer rate. The purpose of thisembodiment is to increase the flow speed as well as the convective heattransfer rate of the working fluid and prevent the heat concentration atthe ends of the pipes by gradually reducing the pipe diameter. Althougha pipe with decreasing pipe diameter is described in this embodiment,the present invention should not be limited thereto. In otherembodiments, in order to achieve the best heat dissipating result, thepipe diameter of each section of the continuous S-shaped pipe of thepresent invention can be varied according to the heat distributionpattern of the electric motor.

FIG. 4A is a 3D view of the cooling jacket according to an embodiment ofthe present invention. FIG. 4B is an illustrative diagram where thecooling jacket in FIG. 4A is “spread” into a 2D plane. In FIG. 4B, thecontinuous S-shaped pipe of the cooling jacket 300 has substantially thesame structure as that in FIG. 2B, and can be divided into three parts:the forwarding portion(s) 410, the reversed portion(s) 420 and theturning portion(s) 430. However, unlike in FIG. 2B, the cooling jacket400 in FIG. 4B has “two” sets of continuous S-shaped pipes 400L and400R. For illustration, the two sets of the continuous S-shaped pipes400L and 400R have the same size (the total length of the pipe 400L or400R is half of that in FIG. 2B), and each pipe 400L or 400R covers halfof the circumference of the electric motor. However, in otherembodiments, these two continuous S-shaped pipes may have differentsizes and cover a different area of the electric motor. Compared withthe embodiment in FIG. 2B (given that the working fluid has the sametemperature at the working fluid inlet in both embodiments of FIGS. 2Band 4B), the working fluid in FIG. 4B flows through a much shorterlength before being expelled, thus removing heat from the electric motormore rapidly. It should be noted that the cooling jacket of the presentinvention may have any number of sets of continuous S-shaped pipes.Specifically, the cooling jacket may have two or more continuousS-shaped pipes. For example, the cooling jacket may have N sets of thecontinuous S-shaped pipes for respectively covering 1/N of thecircumference of the electric motor. FIGS. 5A and 5B show three sets ofcontinuous S-shaped pipes in a cooling jacket 500. Since those skilledin the art can easily understand the structural features of the coolingjacket 500, it will not be described in detail.

FIG. 6A is a 3D view of the cooling jacket according to an embodiment ofthe present invention. FIG. 6B is an illustrative diagram where thecooling jacket in FIG. 4A is “spread” into a 2D plane. The coolingjacket 600 in FIGS. 6A and 6B also has two sets of continuous S-shapedpipes 600E and 600I. However, the turning portions 630E and 630I of thecontinuous S-shaped pipes 600E and 600I have different overall lengths.As shown in FIG. 6B, the turning portion 630E of the continuous S-shapedpipe 600E is connected to the forwarding portion 610E at an angle of 90degrees. It extends along the axis direction of the electric motor for ashort distance L, and is connected to the reversed portion 620E atanother angle of 90 degrees. The turning portion 630I of the pipe 600Iis juxtaposed with the turning portion 630E of the pipe 600E. In thisbetter embodiment, the working fluid inlets 640E of the pipes 600E andworking fluid inlets 640I of the pipes 600I may be on two opposite sidesof the cooling jacket 600 so that the working fluid in the pipes 600Eand 600I can flow in two opposite directions. The purpose of this manneris to further even the heat distribution of the electric motor, thuspreventing the heat concentration at the ends of the cooling jacket.

FIG. 7A is a 3D view of the cooling jacket according to an embodiment ofthe present invention. FIG. 7B is an illustrative diagram where thecooling jacket in FIG. 4A is “spread” into a 2D plane. Similarly, thecooling jacket 700 in FIG. 7B has two sets of continuous S-shaped pipes700R and 700L, and each has the forwarding portions 710, the reversedportions 720 and the turning portions 730. However, different from thatin FIG. 4B, the two pipes 700R and 700L are in a mirrored arrangement,and share the same starting end, i.e., the working fluid inlet 740, andthe same terminating end, i.e., the working fluid outlet 750. Thecooling jacket 700 overcomes the defects of heat concentration aroundthe ends of the spiral shaped pipes in the prior art, and evens the heatdistribution of the electric motor.

FIG. 8 is a schematic diagram of a two-layered cooling jacket accordingto an embodiment of the present invention. The cooling jacket 800 has aninner layer L1 and an outer layer L2, where each layer may havecontinuous S-shaped pipes having the same structure as, or similarstructure to, those described above. The inner layer L1 and the outerlayer L2 are respectively disposed at different circumferences of theelectric motor (having different radiuses). In some embodiments, eachlayer has its own and dependent working fluid inlet and outlet. In someembodiments, the inlets of the two layers may be disposed at oppositesides of the cooling jacket to make the working fluid in the layers flowin opposite directions for preventing heat concentration and improvingheat dissipation. Note that the two-layered cooling jacket is merely forillustration, the present invention should not be limited to any numberof layers.

Those skilled in the art can modify and the combine the cooling jacketsin the previous embodiments according to the spirit of the presentinvention. For example, FIG. 9 shows a combination of the coolingjackets in FIGS. 6A and 7, where the arrangement for the two sets ofcontinuous S-shaped pipes is like that in FIG. 6A but the arrangementfor the inlets and outlets is like that in FIG. 7. The cooling jacket900 in FIG. 9 can prevent the heat concentration around the ends of thepipe, but has better heat distribution than the cooling jacket 600 inFIG. 6A. Since the cooling jacket of the present invention has variousmodifications and combinations, they will not be further discussed.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. On the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A cooling jacket for cooling an electric motorcomprising: one or more continuous S-shaped pipes, covering the electricmotor, for conducting working fluid, wherein each continuous S-shapedpipe at least comprises: a forwarding portion and a reversed portion,respectively extending along two respective circumferential directionswhich are parallel but opposite to each other; and a turning portionconnected between the forwarding portion and the reversed portion. 2.The cooling jacket as claimed in claim 1, wherein the forwardingportions and/or the reversed portions of the continuous S-shaped pipehave unequal pipe diameters.
 3. The cooling jacket as claimed in claim2, wherein the pipe diameter of the continuous S-shaped pipe reducesfrom a working fluid inlet to a working fluid outlet.
 4. The coolingjacket as claimed in claim 1, wherein the cooling jacket has N sets ofthe continuous S-shaped pipes, and each set of the continuous S-shapedpipe covers a part of the electric motor.
 5. The cooling jacket asclaimed in claim 1, wherein the cooling jacket has N sets of thecontinuous S-shaped pipes, and each set of the continuous S-shaped pipecovers 1/N of the circumference of the electric motor.
 6. The coolingjacket as claimed in claim 1, wherein the cooling jacket has two sets ofthe continuous S-shaped pipes, and the starting ends of the two sets ofthe continuous S-shaped pipes share a working fluid inlet.
 7. Thecooling jacket as claimed in claim 1, wherein the cooling jacket has twosets of the continuous S-shaped pipes, and the terminating ends of thetwo sets of the continuous S-shaped pipes share a working fluid outlet.8. The cooling jacket as claimed in claim 1, wherein the flowingdirections of the working fluid in any two sets of the continuousS-shaped pipes are opposite to each other.
 9. The cooling jacket asclaimed in claim 1, further comprising a first continuous S-shaped pipehaving a first forwarding portion, a first reversed portion and a firstturning portion; and a second continuous S-shaped pipe having a secondforwarding portion, a second reversed portion and a second turningportion, wherein each of the first forwarding, reversed and turningportions is respectively juxtaposed to the second forwarding, reversedand turning portions.
 10. The cooling jacket as claimed in claim 1,wherein each set of the continuous S-shaped pipes covers a differentcircumference of the electric motor.